In the Star Trek: Star Charts (p. 66), the location of 23 Earth outposts were depicted on a map of the Beta Quadrant. Outposts 1 to 8 were mentioned in dialogue or were seen on the Z-6 Sector map in "Balance of Terror" and Outpost 23 was mentioned in dialogue in "Future Imperfect". Outpost 1 was constructed in an area of space that been contested over during the Romulan War Theater of Operations (2156-2160).